The word Rafath is used twice in the Holy Qurʾān and it is one of the Qurʾānic vocabulary whose meaning has many confusions and interpretation complications. Part of this variety of interpretative opinions is due to the fact that the ancient commentators and lexicographers, instead of explaining the meaning, explained its examples and perhaps they did not have access to its literal meaning. The evidence indicates that Rafath as a word has become obsolete since the middle of the third century of Hijri, and its abandonment in the following centuries has added to the difficulty of the commentators' work. After showing the ambiguities of the commentators and criticizing their opinions, the present research explains the lexical value of Rafs with a historical linguistic explanation, and especially by using the methods of etymology and comparative study of Semitic. As a result of the debates, it is said that «Raft» literally means «hitting with spreading something» and its use for sexual intercourse, although it is the most common use, is an irony. The use of this term for «blatant sexual words» and «fornication» is also based on permission and based on the same meaning as «sexual intercourse». However, those groups who have taken rafath as meaning «ugly speech» in general, have distanced themselves from both the lexical principle and the Quranic context.